1. Field of the Invention
This invention relates to the flotation barrier or boom art and more particularly to an improved containment barrier or boom.
2. Description of the Prior Art
The increased frequency of contamination of bodies of water such as rivers, harbors, ponds, lakes, oceans, and the like, by, for example, oil spills, has increased the need for effective containment barriers or booms wherein the area of the liquid body having the contamination may be separated from adjacent areas of the liquid body and the contamination contained within the sectioned off area. The contamination may be removed without further contamination of additional areas. Various types of booms have heretofore been utilized for providing the barrier separating the contaminated area from uncontaminated areas. One type of boom that has been widely utilized is a flotation boom, generally fabricated in sections. Each section of the boom may be coupled to adjacent sections to form an entire boom of any desired length deployed in any desired geometrical configuration to contain the contamination area. Such flotation booms have generally incorporated a flotation means floating on the surface of the liquid and a dependent sinking means or skirt extending from the bottom of the flotation means into the liquid. The skirt has a predetermined depth and generally incorporated a ballast and, preferably, a tension member.
The flotation means heretofore utilized has comprised, for example, logs, sealed rigid containers such as oil drums or the like, inflatable tubular members, tubular members filled with a buoyant material, i.e., a material having a specific gravity less than 1.0, or similar devices. However, such prior art flotation means in a containment boom have generally not proven to be completely satisfactory. Since the containment boom is often stored for comparatively long periods of time and only deployed on the liquid when it is necessary to contain a contaminated area, the storage volume is preferably as small as possible. Further, since the contamination may occur quite suddenly, the boom should be able to be rapidly deployed with comparatively low drag and low turbulence inducement in the liquid. Further, it should be deployable without utilizing sophisticated machinery and/or highly skilled labor. Additionally, it is also desired that the boom be capable of articulation in both the horizontal and vertical directions, while maintaining its cross-sectional configuration, in response to the forces imposed to minimize stresses imposed on the boom as well as maintaining desired draft and freeboard and minimizing splash-over. Further, each boom section is preferably fabricated in as longitudinally long sections as possible to reduce the turbulence of mixing effect on deployment or when used, and to reduce costs associated with boom section connections.
One form of inflatable boom heretofore utilized has incorporated a plurality of boom elements, each approximately 25 yards long and has a flotation portion and a dependent skirt portion. The flotation section is a flexible fabric and has a generally rectangular configuration in the deployed condition and is transversely collapsible in the stored condition to a flat configuration in which it may, for example, be coiled. Each element is comprised of a plurality of sections on the order of 1 to 2 yards long. Each section has one or more individual spring loaded, pivotally connected rectangular frames and a check valve for admitting air into the section. In the collapsed, or storage condition, the springs allow the collapse of the rectangular frames to permit the boom to assume the transversely flat storage configuration. Means are provided, in the storage configuration, to resist the spring forces and prevent opening of the boom. On deployment, the restraints are removed and the springs force the rectangular frames into the rectangular configuration opening the tubular member to conform to the rectangular cross-section. Air is drawn into each compartment during the opening of the tubular member through the check valve and the trapped air in the boom, which exceeds atmospheric pressure, provides buoyancy. The trapped air in the boom resists the natural liquid forces acting thereon which tend to transversely collapse the boom and, thus, the combination of the trapped air and the spring loaded frames may be required to maintain buoyancy. On retrieval of the boom section, air must be vented by manual operation of some form of valve and each rectangular frame must be collapsed and means provided to retain the collapsed configuration. Such operating mechanical structures in the interior of the boom, the automatic opening as well as the labor associated with retrieval, have made such boom elements unsatisfactory in many applications.
The logs and the buoyant material filled flotation means have generally required the same volume in a stored condition as in the deployed condition. While some inflatable flotation booms may be stored in a volume less than the deployed volume, they have usually required utilization of an air compressor or similar device to provide a positive pressure on the interior thereof to achieve the desired flotation and buoyancy characteristics.
Many of the prior art booms have been fabricated so that the cross-sectional configuration is not constant for substantial longitudinal lengths, thereby increasing the turbulence inducing effect and increasing the drag. Also, the more rigid of such booms could not provide the desired degree of vertical and/or horizontal articulation within each boom section, resulting in higher stresses imposed because of the forces occurring in use and less containment capability.
Therefore, there has long been a need for a containment boom which not only may be stored in a comparatively small volume comprising a fraction of its fully deployed volume but also may be rapidly and easily deployed from the stored condition to the deployed condition without utilization of highly skilled labor and/or complicated or sophisticated machinery. Also, such booms should be capable of vertical and horizontal articulation is use while maintaining the same cross-sectional configuration and have low drag and turbulence inducing characteristics as well as being fabricated in comparatively longitudinally long sections.